Compression question

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rcsupercat

New Member
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4
Location
Jersey Shore
Greetings all: After 5 years of use it seems like my motor top end might be smoked. It"s a CY 23 in a FG Marder. I removed the engine to get a good look at it. I can spin the the flywheel with one finger. The engine spins all the way throught the compression stroke with almost no resistance.:( I was only getting about 60% or 70% power, which is what leads to to believe the ring or the cylinder is smoked. Anyway... I gues I'm just looking for someone to agree with my diagnosis. I can get a hold of a compresion tester l8tr this week if I need to. What number am I looking for? Guess I will go with a 35mm Big Bore kit. That should solve the problem:rolleyes:
 
sounds like its out of compression, 5 years thats amazing, i can barley get 6 months out of mine but I use it every weekend for long periods.

take the top end off and closley inspect the piston and cylinder. post some pics up if your not sure and we will give you our opinions.
 
5 years is great life for a baja engine. Let me know your secret.

rather than rebuild it I think you may as well get a new engine, the simple reason is that all your moving parts will have excess wear. This engine owes you nothing it might be worth having it as a spare that you can take your time replacing all components over time to hone your mechanical skills.

Some 2 stroke boats guys get 10+ years out of their engines, but then again they don't really get the abuse we give them.
 
big bore

Replaced the stock 32mm piston and cylinder with the 35mm big bore kit:D
What a difference! The bottom end of the motor was in great shape. I figured no need to replace it. Next is a pipe. Lookin at the Jetpro...
 
i run the jetpro, good solid build and excellent top end, not very impressive down low though, ill be changing to a VRC with the bank account permits, might sell my jetpro when I do.
 
i run the jetpro, good solid build and excellent top end, not very impressive down low though, ill be changing to a VRC with the bank account permits, might sell my jetpro when I do.

Hey sperera... The reason I mentioned the Jetpro is because my friend runs one. It's the only pipe I have actually seen, heard and ran against. He runs a Marder Race, 18 pinion, 46 spur, Stock Zenoah 23cc w/Jetpro. I am running Marder(not race version) 18 pinion, 46 spur, Chung Yang 23cc (upgraded to 35mm piston and cylinder) with stock muffler. Using an Etrex GPS the top end resutls are: Marder Race 37.6 mph... My Marder 41.8 mph. While i got him top end his ride is an Animal on the low end. Soooo... I am hoping to get more low end with the Jetpro...has anyone run both the Jetpro and VRC? Results?
 
depends on which jet pro pipe you get too. each has it's own characteristics. I am big on JP pipes. They look good, are tough and come with a lifetime guarantee. I just busted one and Dino is fixing it for free for me. Just have to send it in. And I have a few... mine busted after a t bone and massive cartwheel... amazed that's all that broke too lol

I had the vrc on my other rally. nice pipes but not as tough. awesome power though. if you want a pipe for a particular use, drop Dino an email or give him a call. he'll tell you what pipe to get to achieve what you want. [email protected] 1 800 4 JETPRO is toll free. Once you speak to him, you'll see why I like to deal with him.
 
+1 to what pipe said the JP's are super strong but my personal opinion they all lack bottom end. ive been in touch with dino and may be involved in helping develop a pipe better down low but this wont be for a while.

the VRC are know to be one of if not the best performing pipe on the market but not as touch as the JP's, still tough though. If you want crazy bottom end VRC is the answer but they are loud and don't have a factory silenced option like the JP's.
 
Got to be honest my SS baja had the Jetpro V2 and despite claims by most saying I should have gone with the DOM the V2 never felt out of it's depth low down. I will admit the DOM was better low down but not by much in the real world. But top end is where Jetpro's really have it, they let your engine scream. I love Jetpro's and they are well built.

I believe the V3 pipe is better low down so it might be worth giving it a try.

Don't know anything about the VRC pipes but talking to a few engine builders over here suggests they are not as powerful as claims suggest but I am told they are better suited to engines that deliver big chunks of power in one hit rather than engines built for smooth all over power, so this maybe just down to how the pipe reacts to the engine is coupled too. They certainly look good well built pipes.
 
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ive never owned a VRC personally but go on the threads I read on different forums. Couple of hobby shops also comment when they sell them no other pipe delievers this amount of power.

I had the DOM and changed to Jetpro on my FG MT and much prefer the JP over the DOM.
 
5 years? did you drive it ever.lol my 23cc just lost some top end. i would say it's at about 80% but i have lots of bottum and midrange. i have no leaks and tried different carbs. my buddy said that you should change the rings about every 6 tanks and i've ran over 20 tanks in it and who know's how many the guy who owned it before me. so i would say that i'm ready for a new ring and your definitly ready for a rebuild. one pipe i haven't seen you guy's mention was the cpi. i've seen the guys at the track run dom's/jp's but when i saw the cpi in action his baja was night and day from the bottum to the top.
 
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hey Kreb, I'm just having a tuned engine built for racing with and have been told every 6-10 tanks i should change the piston ring but on stock engines you can let them go a bit longer between changes.

I have also gotthe CPI pipe for the MCD V4 so hopefully I will be pleased with it, I have only heard good reports about it but know onw in the UK sells them so Large Scale RC have sorted me out.
 
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you should be pleased with it. cpi has been making high performance pipes for years for snowmobiles and dirt bikes and now for rc. i never knew about the 6-10 tank thing untill my buddy said something to me. i have a race ported 28.5 thats got maybe 15 tanks on it and it's still got as much power as it did after rebuild. in my opinion i think its just how you take care of it, look at how long yours lasted.
 
6 tanks between ring jobs? Hmm, sounds pretty expensive to me...

I have over 25 gallons (not tanks) ran through my Cy Gp290 (28.5) and it still runs as it did new.

My JetPro silenced Version 1 in my Mt, hates this motor, but it was a screamer with the stock Zen 26. It would flip over onto it's lid with the zen, but it will barely pull the tires with the Cy.
 
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